Swift 3.1 coming in spring 2017, focus quickly switching to Swift 4

Swift 3.1 will make some "additive enhancements to the core language," along with improvements to Linux support and the Swift Package Manager, said Apple's Ted Kremenek. He also promised better overall quality for the compiler and Standard Library.

Sources built with the Swift 3.0 compiler should continue to build with 3.1, Kremenek noted, the only exceptions being fixes that cause it to reject code that should've been tossed out anyway.

Instead of irregular "Developer Previews," Swift 3.1 will emerge in daily downloadable "snapshots" of the release branch — making sure that people can test as many features and bugfixes as possible.

Core development of 3.1 is expected to end on Jan. 16, after which only critical fixes will be implemented before the final release. Attention will already be switching to Swift 4.